Relationship between relaxation embrittlement and atomic cluster structure in amorphous alloys

Abstract

Relationship between relaxation embrittlement and atomic cluster structure was explored by simulation and experimental methods for two amorphous alloys: Zr60Cu30Al10 and Zr50Cu40Al10 (referred to as Zr60 and Zr50, respectively). Simulation results from large-scale molecular dynamics revealed that the Zr50 alloy exhibited a higher content of icosahedral clusters, which increased more obvious during the quenching process compared to the Zr60 alloy. As icosahedral clusters exhibit brittleness similar to quasicrystalline structures, we predicted that the Zr50 alloy would have a higher glass transition temperature Tg and more pronounced relaxation-induced brittleness than the Zr60 alloy based on this observation. To validate the predictions, experimental results confirmed the occurrence of relaxation brittleness in Zr50 and relaxation non-brittleness in Zr60, consistent with the XRD analysis and electron microscope-based three-dimensional reconstruction in terms of icosahedral clusters. The agreement between the simulation calculations and the experimental data provides a reference for understanding the mechanism of relaxation embrittlement in amorphous alloys.